1. Field of the Invention
The present invention relates to a zoom lens, and in particular to a zoom lens suitable for a projector which enlarges and projects an image, and a projector using such a zoom lens.
2. Description of the Related Art
Conventionally, there is a zoom lens of positive lead type in which a lens having positive refractive power is disposed on the most enlargement side to prevent the aperture of a lens disposed on the enlargement side from becoming large.
Japanese Patent Application Laid-Open No. 2003-287680 discusses a zoom lens including six lens units respectively having positive, negative, negative, positive, positive, and positive refractive power disposed in order from the enlargement side, which is the screen side, toward the reduction side, which is the liquid crystal panel side. During zooming from the wide-angle end to the telephoto end, the second lens unit moves to the reduction side, and the third lens unit, the fourth lens unit, and the fifth lens unit move to the enlargement side.
Furthermore, Japanese Patent Application Laid-Open No. 2003-241096 and Japanese Patent Application Laid-Open No. 2005-309061 discuss a zoom lens of positive lead type including five lens units in which the first lens unit having positive refractive power is disposed on the most enlargement side.